1. Field of the Invention
This invention generally relates to a bicycle crank arm. More specifically, the present invention relates to a bicycle crank arm constructed of two or more pieces to reduce weight as compared to a solid metal bicycle crank arm.
2. Background Information
Generally speaking, a conventional bicycle has a diamond-shaped bicycle frame with a pair of wheels rotatably mounted to the frame and a drive train coupled to the frame for driving the rear wheel. The drive train typically has a bicycle crank assembly that is mounted to a cylindrical or tubular hanger tube of the bicycle frame such that the rear wheel is rotated by the rider applying a pedaling force to the bicycle crank assembly. In particular, this pedaling action of the bicycle crank assembly drives a chain that rotates a sprocket mounted to the rear wheel. The bicycle crank assembly usually includes a crank axle that is mounted in a freely rotatable-manner to the hanger tube of the bicycle frame. A crank arm is fastened to each end of the crank axle. The right crank arm typically has one or more sprockets that is attached thereto thr driving the chain, and is fixed to the right end of the crank axle. On the other hand, the left crank arm typically does not include a sprocket and is releasably attached to the left end of the crank axle. As used herein, the terms “right” and “left” are often used to describe bicycle components on the assumption that the bicycle is viewed from the rear.
In the past, the crank arms were typically solid metal members. However, such solid metal crank arms are typically quite heavy. In the bicycle field, bicycle riders are constantly demanding lighter bicycle components in order to decrease the overall weight of the bicycle. In response to this demand, bicycle component manufacturers have produced lighter crank arms by using non-metallic materials and/or providing a hollow space in a body member of the crank arm. The hollow space in the body member of the crank arm is sometimes covered with a cover member.
In view of the above, it will be apparent to those skilled in the art from this disclosure that there exists a need for an improved bicycle crank arm that is lighter than solid metal bicycle crank arm. This invention addresses this need in the art as well as other needs, which will become apparent to those skilled in the art from this disclosure.